This chapter summarizes the current knowledge about Bacillus ribosomes and translation factors. Much of the information concerning Bacillus ribosome structure and function has been obtained from work with Bacillus stearothermophilus, while most of the genetic analysis has been carried out with B. subtilis. Available information about ribosome structure and genetics in other gram-positive systems are also summarized in this chapter. B. subtilis contains 10 rRNA operons.The sequences of the rrnB and rrnO operons have been determined; they show an organizational pattern identical to that of the E. coli rRNA operons, containing genes for 16S, 23S, and 5S rRNA in that order. Ribosomal-protein gene characterization was initiated by the isolation and mapping of mutations conferring resistance to antibiotics that were known to target the translational machinery. A number of mutants that have alterations in components of the translational apparatus and exhibit defects in sporulation have been identified. These include mutants with altered sensitivity to antibiotics that act on the ribosome and temperature-sensitive mutants that result in spore-minus or spore-conditional phenotypes. In E. coli, sequences in the promoter regions of genes sensitive to the stringent response have been identified, and it has been proposed that (p)ppGpp acts directly as an effector in modulating promoter recognition by RNA polymerase. Expression of a fusion of the B. subtilisrrnO promoter to lacZ was repressed by induction of the stringent response by the addition of serine hydroxamate in wild-type strains but not in a relA-minus mutant.

Location of ribosomal genes on the B. subtilis chromosome. Map coordinates (0 to 360°) are indicated on the outside of the circle. The origin of chromosomal replication is at 0°. rRNA operons (rrn) are shown on the inside of the circle. Ribosomal-protein and translation factor genes as well as other genes known to be located within ribosomal gene clusters are shown on the outside of the circle. Arrows indicate the direction of transcription, where known. The rif-str-spc cluster at 12° includes genes for the following: L11-L1-L10-L12-ORF-β-β'-S12-S7-EFG-EFTu-S10-(L3,L4,L23?)-L2-S19-L22-S3-L16-L29-S17-L14-L24-L5-S14-S8-L6-L18-S5-L30-L15-SecY-Adk-Map-IF1-L36-S13-S11-α-L17-ORF--S9-(L13?)--S20, where ORF is an open reading frame. Parenthesis indicate uncertainty in gene localization. Additional genes are also likely to be present in this region. The gene for protein L28 is also located near 145°.

10.1128/9781555818388/fig46-1_thmb.gif

10.1128/9781555818388/fig46-1.gif

Figure 1

Location of ribosomal genes on the B. subtilis chromosome. Map coordinates (0 to 360°) are indicated on the outside of the circle. The origin of chromosomal replication is at 0°. rRNA operons (rrn) are shown on the inside of the circle. Ribosomal-protein and translation factor genes as well as other genes known to be located within ribosomal gene clusters are shown on the outside of the circle. Arrows indicate the direction of transcription, where known. The rif-str-spc cluster at 12° includes genes for the following: L11-L1-L10-L12-ORF-β-β'-S12-S7-EFG-EFTu-S10-(L3,L4,L23?)-L2-S19-L22-S3-L16-L29-S17-L14-L24-L5-S14-S8-L6-L18-S5-L30-L15-SecY-Adk-Map-IF1-L36-S13-S11-α-L17-ORF--S9-(L13?)--S20, where ORF is an open reading frame. Parenthesis indicate uncertainty in gene localization. Additional genes are also likely to be present in this region. The gene for protein L28 is also located near 145°.

26.Dabbs, E. R.1983. Mapping of the genes for Bacillus subtilis ribosomal proteins S6 and S16: comparison of the chromosomal distribution of ribosomal protein genes in this bacterium with the distribution in Esche-richia coliMol. Gen. Genet.192:386–390.

71.Herfurth, E.,, H.Hirano,, and B.Wittmann-Liebold. 1991. The amino-acid sequences of the Bacillus stearo-thermophilus ribosomal proteins S17 and S21 and their comparison to homologous proteins of other ribosomes. Biol. Chem. Hoppe-Seyler372:955–961.

97.Kruft, V.,, and B.Wittmann-Liebold. 1991. Determination of peptide regions on the surface of the eubacterial and archaebacterial ribosome by limited proteolytic digestion. Biochemistry30:11781–11787.

117.Moriya, S.,, N.Ogasawara,, and H.Yoshikawa. 1985. Structure and function of the region of the replication origin of the Bacillus subtilis chromosome. III. Nucleo-tide sequence of some 10,000 base pairs in the origin region. Nucleic Acids Res.13:2251–2265.

119.Neumann-Spallart, C.,, J.Jakowitsch,, M.Kraus,, M.Brandtner,, H. J.Bohnert,, and W.Loffehardt. 1991. rpslO, unreported for plastid DNAs, is located on the cyanelle genome of Cyanophora paradoxa and is cotranscribed with the sir operon genes. Curr. Genet.19:313–315.

127.Ogasawara, N.,, S.Moriya,, and H.Hoshikawa. 1983. Structure and organization of rRNA operons in the region of the replication origin of the Bacillus subtilis chromosome. Nucleic Acids Res.11:6301–6318.

131.Ohama, T.,, F.Yamao,, A.Muto,, and S.Osawa. 1987. Organization and codon usage of the streptomycin operon in Micrococcus luteus, a bacterium with a high genomic G+C content. J. Bacteriol.169:4770–4777.